FLU VACCINE: The Facts, Please . . .

Doctors demand that their patients get an annual flu vaccine, but may not explain why. They usually just say “get it”, because they may be rushed for time.

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LET'S LOOK AT THE EVIDENCE

So how well do the flu vaccine let’s take a look at the best evidence. For that we got to the Cochrane Collaborative, the world’s pre-eminent Evidence Based Medicine (EBM) organization. 

THE REAL DEAL . . .

    "Cochrane contributors - 37,000 from more than 130 countries - 
    
work together to produce credible, accessible health information
   
 that is free from commercial sponsorship and other conflicts of interest. 
    
Many of our contributors are world leaders in their fields - medicine, 
   
health policy, research methodology, or consumer advocacy - and our
  
groups are situated in some of the world's most respected academic
  
 and medical institutions."

Here’s what the they say about the flu vaccine:
                     "The target populations were healthy adults, including pregnant women and newborns."

"Over 200 viruses cause influenza and ILI (influenza like illness), producing the same symptoms (fever, headache, aches, pains, cough and runny noses). Without laboratory tests, doctors cannot distinguish between them as both last for days and rarely lead to death or serious illness. At best, vaccines may only be effective against influenza A and B, which represent about 10% of all circulating viruses. The virus strains contained in the vaccine are usually those that are expected to circulate in the following epidemic seasons (two type A and one B strains)."

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COVERS ONLY 10% OF VIRUSES

COMMENT: As you can see, the viruses covered by the vaccine represent only 10% of the circulating flu viruses. What about all the other 90%? No luck!

SMALL EFFECT, NO WORKING DAYS LOST

"The preventive effect of parenteral inactivated influenza vaccine (injection) on healthy adults is small: at least 40 people would need vaccination to avoid one ILI [influenza like illness] case (95% confidence interval (CI) 26 to 128) and 71 people would need vaccination to prevent one case of influenza (95% CI 64 to 80). Vaccination shows no appreciable effect on working days lost or hospitalization."
 

READ THIS CAREFULLY

COMMENT: So you need to vaccinate 40 people to prevent one case of flu like illness (FLI) -- let’s call it a bad cold. You need to vaccinate 71 people to prevent one case of the actual flu. These numbers mean a 1 in 40 chance (2.5%) for FLI and a 1 in 70 chance (1.4%) for the actual respectively of preventing sickness. 

WHAT THE EXPERTS CONCLUDE

Authors' conclusions: 

Influenza vaccines have a very modest effect in reducing influenza symptoms and working days lost in the general population, including pregnant women.  This review includes 90 studies, 24 of which (26.7%) were funded totally or partially by industry. Out of the 48 RCTs, 17 were industry-funded (35.4%).

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CUT ONCE FOR THE ACE OF SPADES

FINAL COMMENT:  It comes down to this. You’re holding a deck of 52 playing cards in your hand. Shuffle it up a few times. Now cut once -- just once -- for the Ace of Spades. You only have ONE chance to cut for the Ace of Spades -- your approximate chance of the flu vaccine actually keeping you from coming down with the flu. Your chance of coming up with Ace of spades is 1 in 52 (1.9%). That is, slightly more or less than your chance of avoiding the flu or a flu like illness (FLI) when you get a flu vaccine. No so great. Why are folks not told this? 

Let's get the facts straight first.

                                    

Alan Inglis MD
Board Certified Internal Medicine

REFERENCE:
Vaccines to prevent influenza in healthy adults
Authors: 
Demicheli V, Jefferson T, Al-Ansary LA, Ferroni E, Rivetti A, Di Pietrantonj C
Primary Review Group: 
Cochrane Collaborative    13 March 2014